Compressed file system and Encrypting File system

the point to mention here is called encryption. I believe some of my friends are familiar with the two names of Alice and Bob , and these two names were first used in a book published by IBM to explain symmetric and asymmetric cryptography. Symmetric encryption, the simple point is that the password used to encrypt and decrypt the password used is the same password. Asymmetric, the encryption used by the decryption is a different password. This different password, one is called the private key, the other is the public key. As can be seen from the name above, the private key, is not in any way public, public key, it is published.

explain in detail that friends who are familiar with asymmetric encryption can skip this paragraph. E.g.aliceto send a copy of sensitive data toBOB, which clearly requires encryption. Asymmetric encryption, encrypted and decrypted using two different passwords. This means that ifAlicethe public and private keys are a set of passwords, respectively,Alicethe public key andAlice's private key. So, withAlicePublic key encryption is something only usedAlicethe private key can be decrypted, corresponding, if usedAlicePublic Key cryptography is something that onlyAlicethe private key can be undone. Then forBobis the same. If we use symmetric encryption, that is, the process of encryption and decryption using a password, then this password is not intercepted by a third party in any way. Internet, can intercept, telephone, can listen, even in the face of exchange, can be tapped. So this is a major flaw in symmetric cryptography. If asymmetric encryption is used,Aliceand theBobdo not disclose their private keys, and then they exchange the public key before exchanging information. This way,AliceUseBobthe public key encryptionAlicewant to giveBobThe file that this usesBobPublic key encrypted files, onlyBobthe private key can be undone. andBobnever publicly had his private key, so, as we see, such encryption is safe. This information is encrypted and decrypted, and the process of exchanging the public key is asymmetric encryption.

explained asymmetric encryption, we can also simply compare the advantages of both in security. However, asymmetric encryption is an important flaw, that is, the operation time is very long, symmetric encryption in the work efficiency may be asymmetric encryption 100-1000 times. So Microsoft, too, has seen this, integrating the benefits of both in EFS. EFS uses a combination of symmetric and asymmetric encryption to encrypt a file as a string, using symmetric encryption as a key, and then encrypt the key using asymmetric encryption. I can't remember the exact number of bits in this key . There is a problem here, how is the public key and private key obtained in the operating system? Why can an administrator unlock encrypted files for all users?

CA (certificationauthority) Span style= "font-family: ' The song Body '; > and the other is at the enterprise level Ca sid

recently heard that some software can crack Microsoft's EFS, the results of the download after the study, this software works is to back up the administrator's account information, through the ERA ( Emergency Recovery agent ) to achieve the restoration of encrypted files. In fact, if the user accidentally forgets to back up the corresponding key when reinstalling the system, the encrypted file may never open. This is not difficult to understand, because each time the operating system is installed, the operating system will generate a SID number, of course, if the user's character is good enough, still can generate the same Sid number (joking). For backup administrator accounts and passwords, you can use the Forgotten Password Wizard built in Windows2000 and later to help you back up your passwords. I hope we can give you some help.

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Compressed file system and Encrypting File system